Project 3: Arsenic Biomarker Epidemiology. Arsenic is ranked number one on the Superfund Priority List of Hazardous Substances. During the last five years, we have found that early life exposure to arsenic results in major mortality increases among young adults aged 30-49 from lung cancer and bronchiectasis, myocardial infarction, kidney cancer, and bladder cancer. Our Chile studies have recently identified even more causes of death related to arsenic, and show that peak mortality risks are much greater than those from any other environmental exposure anywhere in the worid. We plan to continue our investigation of arsenic exposure and mortality in northern Chile for the years 1950 to 2000, now assessing mortality due to pulmonary tuberculosis, chronic renal failure, and our newly discovered evidence of increased mortality from cancers of the larynx, penis, cervix and thyroid gland. We will also follow a unique cohort of children in Bangladesh who were highly exposed to arsenic in utero and in early childhood, including measuring lung function, assessing the incidence of chronic respiratory disease and upper respiratory tract infections, measuring blood pressure, blood glucose and;ff2-microglobulin, a marker of reduced kidney glomerular filtration rate. We will collect urine samples and buccal cells from Bangladesh and from our ongoing northern Chile eariy life exposure study, to analyze epigenetic alterations and proteomic biomarkers of arsenic exposure, susceptibility, and disease. We will use the northern Chile buccal and urine samples to assess the impact on pulmonary function and respiratory symptoms in adults, decades after high exposure. We will conduct in vitro studies to determine the mechanism and downstream effects involved in the persistent down-regulation of HBDl gene expression by the toxic arsenic metabolite, MMA3. We will also knock down HBDl gene expression in target organ cell lines to detennine the genes that are affected by HBDl down-regulation, in summary, we are proposing an integrated research strategy assessing multiple outcomes from arsenic exposure in population studies, focusing on effects from eariy life exposure, along with pursuing evidence concerning mechanisms of action.